There are two types of linseed flax produced; one is an industrial oil type containing more than 50% linolenic acid. The second type is an edible oil crop containing less than 2% linolenic acid. Solin is an example of a low linolenic type, while the variety Normandy has high levels of linolenic acid.
Mutant strains of flax containing low levels of linolenic acid have been developed using ethyl methanesulphonate (EMS) mutagenesis of high linolenic acid cultivars (Green and Marshall (1984) Euphytica 33:321-328; Rowland (1991) Can. J. Plant Sci. 71:393-39). Mutations in omega-3 desaturase genes, i.e., the genes encoding the enzymes controlling omega-3 fatty acid desaturation, are known to reduce linolenic acid levels in other plants (Browse et al. (1993) J Biol Chem. 268(22):16345-51).
In flax, two genes control the low linolenic acid trait (Green and Marshall (1984); Rowland (1991)) suggesting that flax may contain two omega-3 fatty acid desaturase (FAD3) genes. However, only one FAD3 gene from flax has been isolated (Qiu et al. (2003), WO 02102970) and the mutations resulting in the low linolenic acid trait have not been characterized at the molecular level.
Accordingly, the identification of markers for the linolenic acid trait in flax would be helpful to plant breeders.